Digestive System—Anatomy of the Mouth,
Esophagus, and Stomach
Lecture 14
Today, we’re going to begin a new topic: The digestive system. And
we’re going to start with the anatomy and, again, work slowly into the
physiology of the digestive system in sections. We’re going to start with
the upper digestive system and work our way down.
Lecture 14: Digestive System—Anatomy of the Mouth, Esophagus, and Stomach
T
his is the rst lecture in a six-lecture examination of the digestive
system. We begin by examining the anatomy of the structures through
which food passes before its conversion into nutrients for the body.
We conclude by reviewing the four main functional divisions of the stomach
(the cardia, fundus, body, and antrum) and its various layers.
The digestive system is also known as the gastrointestinal (GI) tract and the
alimentary canal. It is a continuous tube beginning at the lips and ending at
the anus. Embryologically, it forms from a tube-like structure that develops
outpouchings, which in turn evolve into attached digestive organs, such as
the pancreas, liver, gallbladder, and so on. The entire system is about 40 feet
in length; it is designed to transport food and water, modify it, and make it
suitable for absorption and excretion. There are storage sites, excretion sites,
and detoxifying sites along the way.
Food enters the body through the mouth, where it is moistened by saliva for
ease of swallowing. The tongue then pushes the food into the esophagus,
which carries the food to the stomach. Let’s examine this process and the
structures that participate in it in some more detail.
Lips and mouth
The lips function in eating and forming sound.
The mouth is lined with mucous membranes that lubricate its surfaces. The
teeth cut and grind food; cutting teeth are in the front of the mouth, with the
grinding teeth in the back. The roof of the mouth is the hard palate anteriorly
and the soft palate posteriorly.
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, The rear of the mouth is de ned by the soft tissue arch separating the
mouth from the throat. It has two parts: the palatoglossal arch and the
palatopharyngeal arch. Tonsils between the two arches ght infection. The
uvula hangs down from the arch in the midline. It rises during swallowing to
close off the nose from food.
The tongue is the largest muscle mass in the mouth. It functions in chewing,
swallowing, and forming words.
Extrinsic muscles of the tongue attach to the skull and neck, and
they move from side to side and in and out.
Intrinsic muscles attach to the tongue itself, and they alter the
tongue’s shape (for swallowing and speech).
Papillae are the bumps on the tongue that contain taste buds.
There are three pairs of salivary glands in the mouth. They secrete saliva, the
rst of the digestive juices to contact the bolus (a lump or wad of food). The
three pairs of glands are:
Parotid (“near the ear”) glands.
These glands are under the skin on top of the masseter muscle.
A duct passes around the masseter to enter the mouth between
the molars.
Mumps is a viral infection that affects the parotid glands (as
well as the testes and ovaries).
Submandibular glands.
These glands are on the oor of the mouth, just under the
mandibles.
They enter the oor on either side of the frenulum of the tongue.
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Esophagus, and Stomach
Lecture 14
Today, we’re going to begin a new topic: The digestive system. And
we’re going to start with the anatomy and, again, work slowly into the
physiology of the digestive system in sections. We’re going to start with
the upper digestive system and work our way down.
Lecture 14: Digestive System—Anatomy of the Mouth, Esophagus, and Stomach
T
his is the rst lecture in a six-lecture examination of the digestive
system. We begin by examining the anatomy of the structures through
which food passes before its conversion into nutrients for the body.
We conclude by reviewing the four main functional divisions of the stomach
(the cardia, fundus, body, and antrum) and its various layers.
The digestive system is also known as the gastrointestinal (GI) tract and the
alimentary canal. It is a continuous tube beginning at the lips and ending at
the anus. Embryologically, it forms from a tube-like structure that develops
outpouchings, which in turn evolve into attached digestive organs, such as
the pancreas, liver, gallbladder, and so on. The entire system is about 40 feet
in length; it is designed to transport food and water, modify it, and make it
suitable for absorption and excretion. There are storage sites, excretion sites,
and detoxifying sites along the way.
Food enters the body through the mouth, where it is moistened by saliva for
ease of swallowing. The tongue then pushes the food into the esophagus,
which carries the food to the stomach. Let’s examine this process and the
structures that participate in it in some more detail.
Lips and mouth
The lips function in eating and forming sound.
The mouth is lined with mucous membranes that lubricate its surfaces. The
teeth cut and grind food; cutting teeth are in the front of the mouth, with the
grinding teeth in the back. The roof of the mouth is the hard palate anteriorly
and the soft palate posteriorly.
78
, The rear of the mouth is de ned by the soft tissue arch separating the
mouth from the throat. It has two parts: the palatoglossal arch and the
palatopharyngeal arch. Tonsils between the two arches ght infection. The
uvula hangs down from the arch in the midline. It rises during swallowing to
close off the nose from food.
The tongue is the largest muscle mass in the mouth. It functions in chewing,
swallowing, and forming words.
Extrinsic muscles of the tongue attach to the skull and neck, and
they move from side to side and in and out.
Intrinsic muscles attach to the tongue itself, and they alter the
tongue’s shape (for swallowing and speech).
Papillae are the bumps on the tongue that contain taste buds.
There are three pairs of salivary glands in the mouth. They secrete saliva, the
rst of the digestive juices to contact the bolus (a lump or wad of food). The
three pairs of glands are:
Parotid (“near the ear”) glands.
These glands are under the skin on top of the masseter muscle.
A duct passes around the masseter to enter the mouth between
the molars.
Mumps is a viral infection that affects the parotid glands (as
well as the testes and ovaries).
Submandibular glands.
These glands are on the oor of the mouth, just under the
mandibles.
They enter the oor on either side of the frenulum of the tongue.
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